U.S. patent application number 13/500701 was filed with the patent office on 2012-08-09 for method of producing silicon carbide-coated carbon material.
Invention is credited to Yoshitaka Aoki.
Application Number | 20120202069 13/500701 |
Document ID | / |
Family ID | 43856878 |
Filed Date | 2012-08-09 |
United States Patent
Application |
20120202069 |
Kind Code |
A1 |
Aoki; Yoshitaka |
August 9, 2012 |
METHOD OF PRODUCING SILICON CARBIDE-COATED CARBON MATERIAL
Abstract
A method of producing a silicon carbide-coated carbon material
that comprises heating, under a non-oxidizing atmosphere, a carbon
substrate and an amorphous inorganic ceramic material obtained by
heating a non-melting solid silicone, thereby forming a silicon
carbide coating film on the carbon substrate. A silicon
carbide-coated carbon material that exhibits excellent heat
resistance and has a uniform silicon carbide coating can be
obtained.
Inventors: |
Aoki; Yoshitaka;
(Takasaki-shi, JP) |
Family ID: |
43856878 |
Appl. No.: |
13/500701 |
Filed: |
October 7, 2010 |
PCT Filed: |
October 7, 2010 |
PCT NO: |
PCT/JP2010/067665 |
371 Date: |
April 6, 2012 |
Current U.S.
Class: |
428/408 ;
427/249.16 |
Current CPC
Class: |
C04B 2111/00844
20130101; C01B 32/963 20170801; C04B 41/87 20130101; C04B 41/5059
20130101; Y10T 428/30 20150115; C01B 32/05 20170801; C04B 41/009
20130101; C04B 41/5059 20130101; C04B 41/4517 20130101; C04B
41/4554 20130101; C04B 41/4556 20130101; C04B 41/009 20130101; C04B
35/52 20130101 |
Class at
Publication: |
428/408 ;
427/249.16 |
International
Class: |
B32B 9/00 20060101
B32B009/00; C23C 16/00 20060101 C23C016/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 9, 2009 |
JP |
2009-235721 |
Claims
1. A method of producing a silicon carbide-coated carbon material
comprising a carbon substrate and a silicon carbide coating film
that coats the carbon substrate, the method comprising: heating an
amorphous inorganic ceramic material, which comprises silicon,
carbon and oxygen, has an average elemental ratio between the
silicon, carbon and oxygen that is represented by a composition
formula (1) shown below: Si.sub.1C.sub.aO.sub.b (1) wherein a is a
number that satisfies 0.5.ltoreq.a.ltoreq.3.0 and b is a number
that satisfies 1.0.ltoreq.b.ltoreq.4.0, has a siloxane skeleton
composed of Si--O--Si bonds, and has a hydrogen mass fraction of 0
to 0.5% by mass, together with the carbon substrate, in a
non-oxidizing atmosphere at a temperature exceeding 1,500.degree.
C. but not higher than 2,200.degree. C.
2. The method according to claim 1, wherein the amorphous inorganic
ceramic material is obtained by heating a non-melting solid
silicone in a non-oxidizing atmosphere at a temperature of 400 to
1,500.degree. C.
3. The method according to claim 2, wherein the non-melting solid
silicone is a non-melting silicone resin obtained by subjecting a
meltable silicone resin to a non-melting treatment.
4. The method according to claim 3, wherein the meltable silicone
resin is represented by an average composition formula (2) shown
below:
R.sup.1.sub.mR.sup.2.sub.n(OR.sup.3).sub.p(OH).sub.qSiO.sub.(4-m-n-p-q)/2
(2) wherein each R.sup.1 independently represents a hydrogen atom
or a monovalent hydrocarbon group other than an aryl group which
may comprise a carbonyl group, R.sup.2 represents a phenyl group,
R.sup.3 represents a monovalent hydrocarbon group of 1 to 4 carbon
atoms, m represents a number that satisfies 0.1.ltoreq.m.ltoreq.2,
n represents a number that satisfies 0.ltoreq.n.ltoreq.2, p
represents a number that satisfies 0.ltoreq.p.ltoreq.1.5, and q
represents a number that satisfies 0.ltoreq.q.ltoreq.0.35, provided
that p+q>0 and 0.1.ltoreq.m+n+p+q.ltoreq.2.6.
5. The method according to claim 2, wherein the non-melting solid
silicone is a cured product of a curable silicone composition.
6. A method of producing a silicon carbide conjugate according to
claim 5, wherein the curable silicone composition is an organic
peroxide-curable silicone composition or a radiation-curable
silicone composition.
7. The method according to claim 5, wherein the curable silicone
composition is an organic peroxide-curable silicone composition
comprising: (a) an organopolysiloxane containing at least two
alkenyl groups bonded to silicon atoms, (b) an organic peroxide,
and (c) as an optional component, an organohydrogenpolysiloxane
containing at least two hydrogen atoms bonded to silicon atoms, in
an amount that provides 0.1 to 2 mols of hydrogen atoms bonded to
silicon atoms within the component (c) per 1 mol of alkenyl groups
within the entire curable silicone composition.
8. The method according to claim 5, wherein the curable silicone
composition is an ultraviolet light-curable silicone composition
comprising: (d) an ultraviolet light-reactive organopolysiloxane,
and (e) a photopolymerization initiator.
9. The method according to claim 8, wherein the ultraviolet
light-reactive organopolysiloxane of the component (d) is an
organopolysiloxane having at least two ultraviolet light-reactive
groups, represented by a general formula (5a) shown below:
##STR00007## wherein R.sup.6 represents identical or different,
unsubstituted or substituted monovalent hydrocarbon groups that do
not have an ultraviolet light-reactive group, R.sup.7 represents
identical or different groups having an ultraviolet light-reactive
group, R.sup.8 represents identical or different groups having an
ultraviolet light-reactive group, in represents an integer of 5 to
1,000, n represents an integer of 0 to 100, f represents an integer
of 0 to 3, and g represents an integer of 0 to 3, provided that
f+g+n.gtoreq.2.
10. The method according to claim 9, wherein each of the
ultraviolet light-reactive groups is an alkenyl group, alkenyloxy
group, acryloyl group, methacryloyl group, mercapto group, epoxy
group or hydrosilyl group.
11. The method according to claim 8, wherein the ultraviolet
light-reactive organopolysiloxane of the component (d) is an
organopolysiloxane having at least two ultraviolet light-reactive
groups, represented by a general formula (5b) shown below:
##STR00008## wherein R.sup.6 represents identical or different,
unsubstituted or substituted monovalent hydrocarbon groups that do
not have an ultraviolet light-reactive group, R.sup.7 represents
identical or different groups having an ultraviolet light-reactive
group, R.sup.8 represents identical or different groups having an
ultraviolet light-reactive group, m represents an integer of 5 to
1,000, n represents an integer of 0 to 100, f represents an integer
of 0 to 3, g represents an integer of 0 to 3, h represents an
integer of 2 to 4, and i and j each represents an integer of 1 to
3, provided that fi+gj+n.gtoreq.2.
12. The method according to claim 11, wherein each of the
ultraviolet light-reactive groups is an alkenyl group, alkenyloxy
group, acryloyl group, methacryloyl group, mercapto group, epoxy
group or hydrosilyl group.
13. The method according to claim 8, wherein the component (e) is
included in an amount of 0.01 to 10 parts by mass per 100 parts by
mass of the component (d).
14. The method according to claim 5, wherein the curable silicone
composition is an addition-curable silicone composition comprising:
(f) an organopolysiloxane containing at least two alkenyl groups
bonded to silicon atoms, (g) an organohydrogenpolysiloxane
containing at least two hydrogen atoms bonded to silicon atoms, in
an amount that provides 0.1 to 5 mols of hydrogen atoms bonded to
silicon atoms within the component (g) per 1 mol of alkenyl groups
within the entire curable silicone composition, and (h) an
effective amount of a platinum group metal-based catalyst.
15. The method according to claim 5, wherein the curable silicone
composition is a condensation-curable silicone composition
comprising: (i) an organopolysiloxane containing at least two
silanol groups or silicon atom-bonded hydrolyzable groups, (j) a
hydrolyzable silane, a partial hydrolysis-condensation product
thereof, or a combination thereof as an optional component, and (k)
a condensation reaction catalyst as another optional component.
16. A silicon carbide-coated carbon material obtained using the
method defined in claim 1.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method of producing a
material in which a carbon substrate is coated with silicon
carbide.
BACKGROUND ART
[0002] Materials composed of a carbon substrate having a coating of
silicon carbide formed on the surface are chemically stable at both
normal temperatures and high temperatures, and also exhibit
excellent mechanical strength at high temperature, and they are
therefore used as high-temperature materials. In recent years, in
the field of semiconductor production, high-purity silicon
carbide-coated carbon materials having excellent heat resistance
and creep resistance have started to be used as boards or process
tubes or the like within steps for conducting heat treatments of
semiconductor wafers, or conducting thermal diffusion of trace
elements within semiconductor wafers.
[0003] Known methods of producing silicon carbide-coated carbon
materials include a method in which a silicon powder is brought
into contact with the surface of a graphite substrate, and heating
is then performed to initiate a chemical reaction and form a
silicon carbide coating (Patent Document 1), and a method in which
silicon carbide is coated onto the surface of a carbon substrate by
a chemical vapor deposition method (CVD method) (Patent Document
2). However, in the method disclosed in Patent Document 1, residual
raw material silicon remains on the graphite substrate, which can
have an adverse effect on the heat resistance of the obtained
silicon carbide-coated carbon material. Further, in the method
disclosed in Patent Document 2, because the deposition has an
associated directionality, the method is not suitable for achieving
a uniform coating on the surface of a carbon substrate having a
complex shape.
PRIOR ART DOCUMENTS
Patent Documents
[0004] Patent Document 1: JP 10-236893 A [0005] Patent Document 2:
JP 2002-37684 A
SUMMARY OF THE INVENTION
Problems Invention Aims to Solve
[0006] An object of the present invention is to address the
problems associated with the conventional technology described
above, and provide a method of producing a silicon carbide-coated
carbon material that is simple, can form a uniform silicon carbide
coating film across an entire substrate, and yields a silicon
carbide-coated carbon material that exhibits excellent heat
resistance.
Means for Solution of the Problems
[0007] As a result of intensive investigation aimed at addressing
the problems described above, the inventors of the present
invention discovered that the above object could be achieved by
treating an amorphous inorganic ceramic material obtained by
heating a non-melting solid silicone in a non-oxidizing atmosphere
at a temperature of 400 to 1,500.degree. C. and a carbon substrate
under specific conditions.
[0008] In other words, the present invention provides a method of
producing a silicon carbide-coated carbon material comprising a
carbon substrate and a silicon carbide coating film that coats the
carbon substrate, wherein the method comprises:
[0009] heating an amorphous inorganic ceramic material, which
comprises silicon, carbon and oxygen, has an average elemental
ratio between the silicon, carbon and oxygen that is represented by
a composition formula (1) shown below:
Si.sub.1C.sub.aO.sub.b (1)
(wherein a is a number that satisfies 0.5.ltoreq.a.ltoreq.3.0 and b
is a number that satisfies 1.0.ltoreq.b.ltoreq.4.0), has a siloxane
skeleton composed of Si--O--Si bonds, and has a hydrogen mass
fraction of 0 to 0.5% by mass, together with the carbon substrate,
in a non-oxidizing atmosphere at a temperature exceeding
1,500.degree. C. but not higher than 2,200.degree. C.
Effects of the Invention
[0010] According to the production method of the present invention,
the starting raw material is an amorphous inorganic ceramic
material, and is therefore easy to handle.
[0011] The silicon carbide coating formed by the production method
of the present invention is produced by a reaction between
generated silicon monoxide and the carbon substrate, and therefore
the adhesion to the carbon substrate is excellent. Further, because
there is no directionality associated with the formation of the
silicon carbide on the carbon substrate, the silicon carbide
coating is formed with a uniform thickness across the entire carbon
substrate. Accordingly, detachment at the interface between the
carbon substrate and the silicon carbide is unlikely to occur.
[0012] Furthermore, the silicon carbide-coated carbon material
contains no metallic silicon or the like as a residual component,
and therefore exhibits excellent heat resistance.
[0013] A more detailed description of the present invention is
presented below. In this description, "room temperature" refers to
the ambient temperature, which can typically change within a range
from 10 to 35.degree. C.
EMBODIMENTS OF CARRYING OUT THE INVENTION
[0014] In this description, a "solid silicone" describes a silicone
that is solid at room temperature. A silicone is an
organopolysiloxane-based polymer material.
[0015] The term "silicone resin" describes an organopolysiloxane
having a three dimensional structure which comprises branched
siloxane units (namely, trifunctional siloxane units known as T
units and/or tetrafunctional siloxane units known as Q units) as
essential siloxane units. In some cases, the silicone resin may
also include linear siloxane units known as D units and/or
monofunctional siloxane units known as M units that are positioned
at molecular chain terminals.
[0016] Furthermore, in this description, when a polymer material is
described as "non-melting", this means the material has no
softening point. Accordingly, a non-melting polymer material does
not melt as the temperature is raised, but rather undergoes thermal
decomposition. Accordingly, a "non-melting solid silicone"
describes a solid silicone that has no softening point, and a
"non-melting silicone resin" describes a silicone resin that has no
softening point.
[0017] In this description, the "softening point" refers to a
temperature measured in accordance with the softening point test
method (ring and ball method) prescribed in JIS K 2207.
[Carbon Substrate]
[0018] The carbon substrate used in the present invention is
generally a porous solid material composed of graphite or amorphous
carbon and having a predetermined shape and dimensions. There are
no particular limitations on the method used for producing the
carbon substrate, and for example, the carbon substrate can usually
be obtained by subjecting a sinterable carbonaceous powder
(amorphous carbon powder) to cold isostatic pressing (CIP) into a
desired shape such as an angled block or a circular cylindrical
block, and then performing firing, followed by graphitization if
required. The thus obtained block can then be subjected to
machining such as cutting or grinding to obtain the desired final
shape and dimensions. Further, the carbon substrate can also be
obtained by subjecting a sinterable carbonaceous powder to
extrusion molding and firing, and then performing graphitization if
required to obtain a molded item having the desired shape and
dimensions. The carbon substrate obtained in this manner is
generally a porous material having a microporous structure.
[Amorphous Inorganic Ceramic Material]
[0019] The amorphous inorganic ceramic material used in the
production method of the present invention acts as a supply source
of silicon monoxide, and is as described above. Namely, the
amorphous inorganic ceramic material comprises silicon, carbon and
oxygen, has a siloxane skeleton composed of Si--O--Si bonds, has an
average elemental ratio between the silicon, carbon and oxygen that
is represented by a composition formula (1) shown below:
Si.sub.1C.sub.aO.sub.b (1)
(wherein a is a number that satisfies 0.5.ltoreq.a.ltoreq.3.0 and b
is a number that satisfies 1.0.ltoreq.b.ltoreq.4.0), and has a
hydrogen mass fraction of 0 to 0.5% by mass, and preferably 0 to
0.1% by mass.
[0020] The amorphous inorganic ceramic material may also include
other elements besides silicon, carbon, oxygen and hydrogen,
provided the inclusion of these other elements does not impair the
object and effects of the present invention, but the amount of
these other elements is preferably not more than 2.0% by mass, and
more preferably 0 to 1.0% by mass.
[0021] As described in detail in JP 2008-81396 A, the amorphous
inorganic ceramic material can be obtained, for example, by heating
a non-melting solid silicone in a non-oxidizing atmosphere at a
temperature of 400 to 1,500.degree. C.
[0022] Examples of the non-melting solid silicone include
non-melting silicone resins and cured products of curable silicone
compositions. According to the method of the present invention, a
high-purity silicon carbide coating is generally obtained, and
particularly in the semiconductor field, a coating containing
minimal detrimental impurity elements such as Fe, CR, Ni, Al, Ti,
Cu, Na, Zn, Ca, ZR, Mg and B can be obtained. In this regard, the
use of a non-melting silicone resin or a cured product of an
organic peroxide-curable silicone composition or a
radiation-curable silicone composition as the non-melting solid
silicone is particularly effective.
--Non-Melting Silicone Resin--
[0023] The non-melting silicone resin is obtained by subjecting a
meltable silicone resin to a non-melting treatment. This
non-melting treatment can be performed, for example, by treating
the meltable silicone resin with an inorganic acid. By performing
this non-melting treatment, the silicone resin becomes non-meltable
in the subsequent heating treatment performed under a non-oxidizing
atmosphere.
[0024] In this description, a "meltable silicone resin" describes a
silicone resin that is a solid at room temperature, but has a
softening point. As the temperature is raised, the silicone resin
either melts or softens at the softening point.
[0025] Examples of the inorganic acid used in the non-melting
treatment described above include gaseous acids such as hydrogen
chloride gas, and liquid acids such as hydrochloric acid and
sulfuric acid. The type and concentration of the inorganic acid can
be selected appropriately in accordance with the amount of phenyl
groups contained within the silicone resin used as the raw
material. In those cases where the amount of phenyl groups within
the silicone resin is low, for example in those cases where the
ratio of phenyl groups relative to the combined total of organic
groups and hydroxyl groups bonded to silicon atoms within the
silicone resin (hereinafter, this ratio is referred to as the
"phenyl group content") is within a range from 0 to 5 mol %, the
use of hydrochloric acid with a concentration of not more than 50%
by mass is preferred, the use of hydrochloric acid with a
concentration of not more than 30% by mass is more preferred, and
the use of hydrochloric acid with a concentration of 10 to 25% by
mass is particularly desirable. In contrast, in those cases where
the phenyl group content within the silicone resin is high, for
example in cases where the phenyl group content exceeds 5 mol % but
is not more than 25 mol %, the use of hydrogen chloride gas or
concentrated sulfuric acid or the like is preferred. By using such
an acid, the non-melting treatment reaction can proceed rapidly
even in those cases where the large amount of phenyl groups causes
significant steric hindrance.
[0026] Examples of the meltable silicone resin include silicone
resins represented by an average composition formula (2) shown
below:
R.sup.1.sub.mR.sup.2.sub.n(OR.sup.3).sub.p(OH).sub.qSiO.sub.(4-m-n-p-q)/-
2 (2)
wherein each R.sup.1 independently represents a hydrogen atom or an
identical or different monovalent hydrocarbon group other than an
aryl group which may comprise a carbonyl group, R.sup.2 represents
a phenyl group, R.sup.3 represents identical or different
monovalent hydrocarbon groups of 1 to 4 carbon atoms, m represents
a number that satisfies 0.1.ltoreq.m.ltoreq.2, n represents a
number that satisfies 0.ltoreq.n.ltoreq.2, p represents a number
that satisfies 0.ltoreq.p.ltoreq.1.5, and q represents a number
that satisfies 0.ltoreq.q.ltoreq.0.35, provided that p+q>0 and
0.1.ltoreq.m+n+p+q.ltoreq.2.6.
[0027] Each of the R.sup.1 groups preferably represents,
independently, either a hydrogen atom, or a monovalent hydrocarbon
group other than an aryl group, which is the same as, or different
from, the other R.sup.1 groups, may comprise a carbonyl group, and
contains from 1 to 8 carbon atoms. Specific examples of R.sup.1
include alkyl groups such as a methyl group, ethyl group, propyl
group, butyl group, pentyl group and hexyl group; cycloalkyl groups
such as a cyclopentyl group and cyclohexyl group; alkenyl groups
such as a vinyl group, allyl group, propenyl group, isopropenyl
group and butenyl group; and acyl groups such as an acryloyl group
and methacryloyl group. From the viewpoint of ease of availability
of the raw material, R.sup.1 is preferably a hydrogen atom, methyl
group, ethyl group or vinyl group.
[0028] The aforementioned m is a number that satisfies
0.1.ltoreq.m.ltoreq.2, but m is preferably not more than 1.5, and m
is preferably not less than 0.1, and more preferably 0.5 or
greater. Provided m satisfies this range, mass loss during the
inorganic ceramization performed by heating can be more readily
suppressed.
[0029] The R.sup.2 group is a phenyl group, and has the function of
increasing the melting point or softening point of the meltable
silicone resin, and can therefore be used to adjust the viscosity
and fluidity of the silicone resin to appropriate levels.
[0030] The aforementioned n is a number that satisfies
0.ltoreq.n.ltoreq.2, but n is preferably not more than 1.5, and n
is preferably not less than 0.05, and more preferably 0.1 or
greater. Provided n satisfies this range, the phenyl group content
is not too high, and mass loss during the inorganic ceramization
performed by heating the non-melting silicone resin can be more
readily suppressed.
[0031] Specific examples of R.sup.3 include alkyl groups of 1 to 4
carbon atoms such as a methyl group, ethyl group, propyl group,
isopropyl group, butyl group and isobutyl group, and a methyl group
is particularly preferred industrially. If R.sup.3 is a monovalent
hydrocarbon group containing 5 or more carbon atoms, then the
reactivity of the group represented by OR.sup.3 tends to be poor,
which means the mass loss tends to be large during the inorganic
ceramization performed by heating the non-melting silicone
resin.
[0032] The aforementioned p indicates the amount of hydrocarbyloxy
groups represented by OR.sup.3, and is a number that satisfies
0.ltoreq.p.ltoreq.1.5, but p is preferably not more than 1.2, and p
is preferably not less than 0.05, and more preferably 0.1 or
greater. Provided p satisfies this range, the hydrocarbyloxy group
content within the silicone resin is not too high, and the
molecular weight of the silicone resin can be more easily
maintained at a high value. Accordingly, mass loss caused by
elimination of silicon and carbon during the inorganic ceramization
performed by heating the non-melting silicone resin can be
suppressed.
[0033] The aforementioned q indicates the amount of silanol groups
and is a number that satisfies 0.ltoreq.q.ltoreq.0.35, is
preferably a number that satisfies 0.ltoreq.q.ltoreq.0.3, and is
most preferably 0. The value of q represents the small amount of
residual silanol groups retained within the meltable silicone resin
during production. Provided the value of q falls within the above
range, the reactivity of the silanol groups can be suppressed for
the meltable silicone resin as a whole, and the storage stability
of the meltable silicone resin can be improved.
[0034] The value of p+q indicates the combined amount of
hydrocarbyloxy groups and silanol groups, wherein p+q>0. The
hydrocarbyloxy groups (preferably alkoxy groups) and/or silanol
groups are necessary for forming cross-linking via
hydrolysis-condensation reactions during the non-melting treatment
described below. The combination of these groups preferably
represents 1 to 15% by mass, and more preferably 2 to 10% by mass,
of the meltable silicone resin.
[0035] The value of m+n+p+q is a number that satisfies:
0.1.ltoreq.m+n+p+q.ltoreq.2.6. Provided the value of m+n+p+q
satisfies this range, mass loss during the inorganic ceramization
performed by heating the non-melting silicone resin can be better
suppressed.
[0036] The molecular weight of the meltable silicone resin is
preferably such that the resin has an appropriate softening point
as described above. For example, the weight-average molecular
weight measured using gel permeation chromatography (hereinafter
abbreviated as GPC) and referenced against polystyrene standards is
preferably at least 600, and is more preferably within a range from
1,000 to 10,000.
[0037] There are no particular limitations on the meltable silicone
resin, provided it satisfies the conditions described above,
although a silicone resin that includes methyl groups within the
molecule is preferred. The meltable silicone resin may be either a
single resin, or a combination of two or more resins with different
molecular structures or different proportions of the various
siloxane units within the resins.
[0038] These types of meltable silicone resins can be produced by
conventional methods. For example, the target meltable silicone
resin can be produced by conducting a cohydrolysis, if required in
the presence of an alcohol of 1 to 4 carbon atoms, of the
organochlorosilanes that correspond with the siloxane units
incorporated within the structure of the target resin, using a
ratio between the organochlorosilanes that reflects the ratio
between the corresponding siloxane units, while removing the
by-product hydrochloric acid and low boiling point components.
Furthermore, in those cases where alkoxysilanes, silicone oils or
cyclic siloxanes are used as the starting raw materials, the target
silicone resin can be obtained by using an acid catalyst such as
hydrochloric acid, sulfuric acid or methanesulfonic acid, adding
water to effect the hydrolysis if required, and following
completion of the polymerization reaction, removing the acid
catalyst and low boiling point components.
--Cured Product of Curable Silicone Composition--
[0039] A cured product of a curable silicone composition can also
be used as the non-melting solid silicone used as a starting raw
material in the above production method.
[0040] This type of curable silicone composition can employ a
conventional composition. Specific examples thereof include organic
peroxide-curable, addition-curable, radiation-curable and
condensation-curable silicone compositions.
[0041] Examples of radiation-curable silicone compositions include
ultraviolet light-curable silicone compositions and electron
beam-curable silicone compositions.
[0042] Examples of organic peroxide-curable silicone compositions
include silicone compositions that undergo curing via a radical
polymerization, in the presence of an organic peroxide, of a linear
organopolysiloxane having alkenyl groups such as vinyl groups at a
molecular chain terminal (either at one terminal or at both
terminals), or at non-terminal positions within the molecular
chain, or at both of these positions.
[0043] Examples of ultraviolet light-curable silicone compositions
include silicone compositions that undergo curing as a result of
the energy of ultraviolet light having a wavelength of 200 to 400
nm. In this case, there are no particular limitations on the curing
mechanism. Specific examples of these compositions include acrylic
silicone-based silicone compositions comprising an
organopolysiloxane containing acrylic groups or methacrylic groups,
and a photopolymerization initiator, mercapto-vinyl addition
polymerization-based silicone compositions comprising a mercapto
group-containing organopolysiloxane, an organopolysiloxane that
contains alkenyl groups such as vinyl groups, and a
photopolymerization initiator, addition reaction-based silicone
compositions that use the same platinum group metal-based catalysts
as heat-curable, addition reaction-type compositions, and cationic
polymerization-based silicone compositions comprising an
organopolysiloxane containing epoxy groups, and an onium salt
catalyst, and any of these compositions can be used as an
ultraviolet light-curable silicone composition.
[0044] Examples of electron beam-curable silicone compositions that
can be used include any of the silicone compositions that are cured
by a radical polymerization that is initiated by irradiating an
organopolysiloxane containing radical polymerizable groups with an
electron beam.
[0045] Examples of addition-curable silicone compositions include
silicone compositions that are cured by reacting an aforementioned
linear organopolysiloxane having alkenyl groups with an
organohydrogenpolysiloxane (via a hydrosilylation addition
reaction) in the presence of a platinum group metal-based
catalyst.
[0046] Examples of condensation-curable silicone compositions
include silicone compositions that are cured by conducting a
reaction between an organopolysiloxane with both terminals blocked
with silanol groups, and an organohydrogenpolysiloxane or a
hydrolyzable silane such as a tetraalkoxysilane or an
organotrialkoxysilane and/or a partial hydrolysis-condensation
product thereof, in the presence of a condensation reaction
catalyst such as an organotin-based catalyst, or silicone
compositions that are cured by reacting an organopolysiloxane with
both terminals blocked with trialkoxy groups, dialkoxyorgano
groups, trialkoxysiloxyethyl groups or dialkoxyorganosiloxyethyl
groups, in the presence of a condensation reaction catalyst such as
an organotin-based catalyst.
[0047] Each of the above reactive silicone compositions is
described below in detail.
Organic Peroxide-Curable Silicone Compositions
[0048] Specific examples of organic peroxide-curable silicone
compositions include compositions comprising:
[0049] (a) an organopolysiloxane containing at least two alkenyl
groups bonded to silicon atoms,
[0050] (b) an organic peroxide, and, as an optional component
[0051] (c) an organohydrogenpolysiloxane containing at least two
hydrogen atoms bonded to silicon atoms (namely, SiH groups), in an
amount that provides 0.1 to 2 mols of hydrogen atoms bonded to
silicon atoms within the component (c) per 1 mol of alkenyl groups
within the entire curable silicone composition.
Component (a)
[0052] The organopolysiloxane of the component (a) is the base
polymer of the organic peroxide-curable silicone composition. There
are no particular limitations on the polymerization degree of the
organopolysiloxane of the component (a), and organopolysiloxanes
that are liquid at 25.degree. C. through to natural rubber-type
organopolysiloxanes can be used as the component (a), but the
average polymerization degree is preferably within a range from 50
to 20,000, more preferably from 100 to 10,000, and still more
preferably from 100 to approximately 2,000. Further, from the
viewpoint of ease of availability of the raw material, the
organopolysiloxane of the component (a) is preferably basically a
linear structure with no branching, in which the molecular chain is
composed of repeating diorganosiloxane units
(R.sup.4.sub.2SiO.sub.2/2 units) and both molecular chain terminals
are blocked with triorganosiloxy groups (R.sup.4.sub.3SiO.sub.1/2)
or hydroxydiorganosiloxy groups ((HO)R.sup.4.sub.2SiO.sub.1/2
units), or a cyclic structure with no branching in which the
molecular chain is composed of repeating diorganosiloxane units,
although the structure may partially include some branched
structures such as trifunctional siloxane units or SiO.sub.2 units.
In the above description, R.sup.4 is as defined below within the
description of formula (3).
[0053] Examples of organopolysiloxanes that can be used as the
component (a) include organopolysiloxanes having at least two
alkenyl groups within each molecule, as represented by an average
composition formula (3) shown below:
R.sup.4.sub.aSiO.sub.(4-a)/2 (3)
wherein R.sup.4 represents identical or different, unsubstituted or
substituted monovalent hydrocarbon groups of 1 to 10 carbon atoms,
and preferably 1 to 8 carbon atoms, 50 to 99 mol % of the R.sup.4
groups are alkenyl groups, and a represents a positive number
within a range from 1.5 to 2.8, preferably from 1.8 to 2.5, and
more preferably from 1.95 to 2.05
[0054] Specific examples of R.sup.4 include alkyl groups such as a
methyl group, ethyl group, propyl group, butyl group, pentyl group
and hexyl group; aryl groups such as a phenyl group, tolyl group,
xylyl group and naphthyl group; cycloalkyl groups such as a
cyclopentyl group and cyclohexyl group; alkenyl groups such as a
vinyl group, allyl group, propenyl group, isopropenyl group and
butenyl group; and groups in which some or all of the hydrogen
atoms within one of the above hydrocarbon groups have each been
substituted with a halogen atom such as a fluorine atom, bromine
atom or chlorine atom, or a cyano group or the like, including a
chloromethyl group, chloropropyl group, bromoethyl group,
trifluoropropyl group and cyanoethyl group, although from the
viewpoint of achieving high purity, the R.sup.4 groups are
preferably composed solely of hydrocarbon groups.
[0055] In this case, at least two of the R.sup.4 groups represent
alkenyl groups (and in particular, alkenyl groups that preferably
contain from 2 to 8 carbon atoms, and more preferably from 2 to 6
carbon atoms). The alkenyl group content among the total of all the
organic groups bonded to silicon atoms (that is, among all the
unsubstituted and substituted monovalent hydrocarbon groups
represented by R.sup.4 within the above average composition formula
(3)) is preferably within a range from 50 to 99 mol %, and more
preferably from 75 to 95 mol %. In those cases where the
organopolysiloxane of the component (a) has a linear structure,
these alkenyl groups may be bonded solely to silicon atoms at the
molecular chain terminals, solely to non-terminal silicon atoms
within the molecular chain, or to both these types of silicon
atoms.
Component (b)
[0056] The component (b) is an organic peroxide that is used as a
catalyst for accelerating the cross-linking reaction of the
component (a) in the organic peroxide-curable organopolysiloxane
composition. Any conventional organic peroxide can be used as the
component (b), provided it is capable of accelerating the
cross-linking reaction of the component (a). Specific examples of
the component (b) include benzoyl peroxide, 2,4-dichlorobenzoyl
peroxide, p-methylbenzoyl peroxide, o-methylbenzoyl peroxide,
2,4-dicumyl peroxide, 2,5-dimethyl-bis(2,5-t-butylperoxy)hexane,
di-t-butyl peroxide, t-butyl perbenzoate and
1,1-bis(t-butylperoxycarboxy)hexane, although this is not an
exhaustive list.
[0057] The amount added of the component (b) must be an amount that
is effective as a catalyst for accelerating the cross-linking
reaction of the component (a). This amount is preferably within a
range from 0.1 to 10 parts by mass, and more preferably from 0.2 to
2 parts by mass, per 100 parts by mass of the component (a). If the
amount added of the component (b) is less than 0.1 parts by mass
per 100 parts by mass of the component (a), then the time required
for curing lengthens, which is economically undesirable. Further,
if the amount added exceeds 10 parts by mass per 100 parts by mass
of the component (a), then foaming caused by the component (b)
tends to occur, and the strength and heat resistance of the cured
reaction product tend to be adversely affected.
Component (c)
[0058] The organohydrogenpolysiloxane of the component (c), which
is an optional component, contains at least two (typically from 2
to 200), and preferably three or more (typically from 3 to 100)
hydrogen atoms bonded to silicon atoms (SiH groups). Even when only
the component (a) is used, curing can be achieved by adding the
component (b) and heating, but by also adding the component (c),
because the reaction with the component (a) proceeds readily,
curing can be performed at a lower temperature and within a shorter
period of time than the case where only the component (a) is used.
There are no particular limitations on the molecular structure of
the component (c), and conventionally produced linear, cyclic,
branched, or three dimensional network (resin-like)
organohydrogenpolysiloxanes can be used as the component (c). In
those cases where the component (c) has a linear structure, the SiH
groups may be bonded solely to silicon atoms at the molecular chain
terminals or solely to non-terminal silicon atoms within the
molecular chain, or may also be bonded to both these types of
silicon atoms. Furthermore, the number of silicon atoms within each
molecule (or the polymerization degree) is typically within a range
from 2 to 300, and is preferably from 4 to approximately 150. An
organohydrogenpolysiloxane that is liquid at room temperature
(25.degree. C.) can be used particularly favorably as the component
(c).
[0059] Examples of the component (c) include
organohydrogenpolysiloxanes represented by an average composition
formula (4) shown below:
R.sup.5.sub.bH.sub.cSO.sub.(4-b-c)/2 (4)
wherein R.sup.5 represents identical or different, unsubstituted or
substituted monovalent hydrocarbon groups containing no aliphatic
unsaturated bonds and containing 1 to 10 carbon atoms, and
preferably 1 to 8 carbon atoms, and b and c represent positive
numbers that preferably satisfy 0.7.ltoreq.b.ltoreq.2.1,
0.001.ltoreq.e.ltoreq.1.0 and 0.8.ltoreq.b+c.ltoreq.3.0, and more
preferably satisfy 1.0.ltoreq.b.ltoreq.2.0,
0.01.ltoreq.c.ltoreq.1.0 and 1.5.ltoreq.b+c.ltoreq.2.5.
[0060] Examples of R.sup.5 include the same groups as those
described above for R.sup.4 within the above average composition
formula (3) (but excluding the alkenyl groups).
[0061] Specific examples of organohydrogenpolysiloxanes represented
by the above average composition formula (4) include
1,1,3,3-tetramethyldisiloxane,
1,3,5,7-tetramethylcyclotetrasiloxane,
tris(hydrogendimethylsiloxy)methylsilane,
tris(hydrogendimethylsiloxy)phenylsilane,
methylhydrogencyclopolysiloxane, cyclic copolymers of
methylhydrogensiloxane and dimethylsiloxane,
methylhydrogenpolysiloxane with both terminals blocked with
trimethylsiloxy groups, copolymers of methylhydrogensiloxane and
dimethylsiloxane with both terminals blocked with trimethylsiloxy
groups, dimethylpolysiloxane with both terminals blocked with
methylhydrogensiloxy groups, copolymers of methylhydrogensiloxane
and dimethylsiloxane with both terminals blocked with
methylhydrogensiloxy groups, copolymers of methylhydrogensiloxane
and diphenylsiloxane with both terminals blocked with
trimethylsiloxy groups, copolymers of methylhydrogensiloxane,
diphenylsiloxane and dimethylsiloxane with both terminals blocked
with trimethylsiloxy groups, copolymers of methylhydrogensiloxane,
methylphenylsiloxane and dimethylsiloxane with both terminals
blocked with trimethylsiloxy groups, copolymers of
methylhydrogensiloxane, diphenylsiloxane and dimethylsiloxane with
both terminals blocked with methylhydrogensiloxy groups, copolymers
of methylhydrogensiloxane, methylphenylsiloxane and
dimethylsiloxane with both terminals blocked with
methylhydrogensiloxy groups, copolymers composed of
(CH.sub.3).sub.2HSiO.sub.1/2 units, (CH.sub.3).sub.2SiO.sub.2/2
units and SiO.sub.4/2 units, copolymers composed of
(CH.sub.3).sub.2HSiO.sub.1/2 units and SiO.sub.4/2 units, and
copolymers composed of (CH.sub.3).sub.2HSiO.sub.1/2 units,
SiO.sub.4/2 units, and (C.sub.6H.sub.5).sub.3SiO.sub.1/2 units.
[0062] The amount added of the component (c) is arbitrary, but is
preferably within a range from 0 to 100 parts by mass, and more
preferably from 0 to 50 parts by mass, per 100 parts by mass of the
component (a). If the amount added of the component (c) exceeds 100
parts by mass per 100 parts by mass of the component (a), then
foaming caused by the component (c) tends to occur, and the
strength and heat resistance of the cured reaction product tend to
be adversely affected.
Ultraviolet Light-Curable Silicone Compositions
[0063] Specific examples of ultraviolet light-curable silicone
compositions include compositions comprising:
[0064] (d) an ultraviolet light-reactive organopolysiloxane,
and
[0065] (e) a photopolymerization initiator.
Component (d)
[0066] The ultraviolet light-reactive organopolysiloxane of the
component (d) typically functions as the base polymer in the
ultraviolet light-curable silicone composition. Although there are
no particular limitations on the component (d), the component (d)
is preferably an organopolysiloxane containing at least two, more
preferably from 2 to 20, and most preferably from 2 to 10,
ultraviolet light-reactive groups within each molecule. The
plurality of ultraviolet light-reactive groups that exist within
this organopolysiloxane may be the same or different.
[0067] From the viewpoint of ease of availability of the raw
material, the organopolysiloxane of the component (d) is preferably
basically either a linear structure with no branching, in which the
molecular chain (the main chain) is composed of repeating
diorganosiloxane units (R.sup.4.sub.2SiO.sub.2/2 units), and both
molecular chain terminals are blocked with triorganosiloxy groups
(R.sup.4.sub.3SiO.sub.1/2), or a cyclic structure with no branching
in which the molecular chain is composed of repeating
diorganosiloxane units, although the structure may partially
include some branched structures such as trifunctional siloxane
units or SiO.sub.2 units. In the above description, R.sup.4 is the
same as defined above in relation to formula (3). In those cases
where the organopolysiloxane of the component (d) has a linear
structure, the ultraviolet light-reactive groups may exist solely
at the molecular chain terminals or solely at non-terminal
positions within the molecular chain, or may also exist at both
these positions, although structures containing ultraviolet
light-reactive groups at least at both molecular chain terminals
are preferred.
[0068] Examples of the ultraviolet light-reactive groups include
alkenyl groups such as a vinyl group, allyl group and propenyl
group; alkenyloxy groups such as a vinyloxy group, allyloxy group,
propenyloxy group and isopropenyloxy group; aliphatic unsaturated
groups other than alkenyl groups, such as an acryloyl group and
methacryloyl group; as well as an epoxy group and hydrosilyl group,
and of these, an acryloyl group, methacryloyl group, mercapto
group, epoxy group or hydrosilyl group is preferred, and an
acryloyl group or methacryloyl group is particularly desirable.
[0069] Although there are no particular limitations on the
viscosity of the organopolysiloxane, the viscosity at 25.degree. C.
is preferably within a range from 100 to 1,000,000 mPas, more
preferably from 200 to 500,000 mPas, and still more preferably from
200 to 100,000 mPas.
[0070] Examples of preferred forms of the component (d) include
organopolysiloxanes containing at least two ultraviolet
light-reactive groups, represented by either a general formula (5a)
shown below:
##STR00001##
wherein R.sup.6 represents identical or different, unsubstituted or
substituted monovalent hydrocarbon groups that contain no
ultraviolet light-reactive groups, R.sup.7 represents identical or
different groups that contain an ultraviolet light-reactive group,
R.sup.8 represents identical or different groups that contain an
ultraviolet light-reactive group, m represents an integer of 5 to
1,000, n represents an integer of 0 to 100, f represents an integer
of 0 to 3, and g represents an integer of 0 to 3, provided that
f+g+n.gtoreq.2,
[0071] or a general formula (5b) shown below:
##STR00002##
wherein R.sup.6, R.sup.7, R.sup.8, m, n, f and g are as defined
above for the general formula (5a), h represents an integer of 2 to
4, and i and j each represents an integer of 1 to 3, provided that
fi+gj+n.gtoreq.2.
[0072] In the above general formulas (5a) and (5b), R.sup.6
represents identical or different, unsubstituted or substituted
monovalent hydrocarbon groups that contain no ultraviolet
light-reactive groups and preferably contain from 1 to 20 carbon
atoms, more preferably from 1 to 10 carbon atoms, and most
preferably from 1 to 8 carbon atoms. Examples of the monovalent
hydrocarbon groups represented by R.sup.6 include alkyl groups such
as a methyl group, ethyl group, propyl group, butyl group, pentyl
group and hexyl group; aryl groups such as a phenyl group, tolyl
group, xylyl group and naphthyl group; cycloalkyl groups such as a
cyclopentyl group, cyclohexyl group and cyclopentyl group; aralkyl
groups such as a benzyl group and phenylethyl group; and groups in
which some or all of the hydrogen atoms within one of the above
hydrocarbon groups have each been substituted with a halogen atom,
cyano group or carboxyl group or the like, including a chloromethyl
group, chloropropyl group, bromoethyl group, trifluoropropyl group,
cyanoethyl group and 3-cyanopropyl group, and of these, a methyl
group or phenyl group is preferred, and a methyl group is
particularly desirable. Furthermore, the monovalent hydrocarbon
group represented by R.sup.3 may also include one or more sulfonyl
groups, ether linkages (--O--) and/or carbonyl groups or the like
within the group structure.
[0073] In the above general formulas (5a) and (5b), examples of the
ultraviolet light-reactive groups contained within the groups
R.sup.7 and R.sup.8 include alkenyl groups such as a vinyl group,
ally group and propenyl group; alkenyloxy groups such as a vinyloxy
group, allyloxy group, propenyloxy group and isopropenyloxy group;
aliphatic unsaturated groups other than alkenyl groups, such as an
acryloyl group and methacryloyl group; as well as a mercapto group,
epoxy group and hydrosilyl group, and of these, an acryloyl group,
methacryloyl group, epoxy group or hydrosilyl group is preferred,
and an acryloyl group or methacryloyl group is particularly
desirable. Accordingly, the groups comprising an ultraviolet
light-reactive group represented by R.sup.7 and R.sup.8 are
monovalent groups that contain any of the above ultraviolet
light-reactive groups, and specific examples of R.sup.7 and R.sup.8
include a vinyl group, allyl group, 3-glycidoxypropyl group,
2-(3,4-epoxycyclohexyl)ethyl group, 3-methacryloyloxypropyl group,
3-acryloyloxypropyl group, 3-mercaptopropyl group,
2-{bis(2-methacryloyloxyethoxy)methylsilyl}ethyl group,
2-{bis(2-acryloyloxyethoxy)methylsilyl}ethyl group,
2-{(2-acryloyloxyethoxy)dimethylsilyl}ethyl group,
2-{bis(1,3-dimethacryloyloxy-2-propoxy)methylsilyl}ethyl group,
2-{(1,3-dimethacryloyloxy-2-propoxy)dimethylsilyl}ethyl group,
2-{bis(1-acryloyloxy-3-methacryloyloxy-2-propoxy)methylsilyl}ethyl
group and
2-{bis(1-acryloyloxy-3-methacryloyloxy-2-propoxy)dimethylsilyl}ethyl
group, and examples of preferred groups include a
3-methacryloyloxypropyl group, 3-acryloyloxypropyl group,
2-{bis(2-methacryloyloxyethoxy)methylsilyl}ethyl group,
2-{bis(2-acryloyloxyethoxy)methylsilyl}ethyl group,
2-{(2-acryloyloxyethoxy)dimethylsilyl}ethyl group,
2-{(1,3-dimethacryloyloxy-2-propoxy)dimethylsilyl}ethyl group,
2-{bis(1-acryloyloxy-3-methacryloyloxy-2-propoxy)methylsilyl}ethyl
group and
2-{bis(1-acryloyloxy-3-methacryloyloxy-2-propoxy)dimethylsilyl}ethyl
group. R.sup.7 and R.sup.8 may be either the same or different, and
individual R.sup.7 and R.sup.8 groups may be the same as, or
different from, other R.sup.7 and R.sup.8 groups.
[0074] In the above general formulas (5a) and (5b), m is typically
an integer of 5 to 1,000, preferably an integer of 10 to 800, and
more preferably an integer of 50 to 500. n is typically an integer
of 0 to 100, preferably an integer of 0 to 50, and more preferably
an integer of 0 to 20. f is an integer of 0 to 3, preferably an
integer of 0 to 2, and more preferably 1 or 2. g is an integer of 0
to 3, preferably an integer of 0 to 2, and more preferably 1 or 2.
In the above general formula (5b), h is typically an integer of 2
to 4, and is preferably 2 or 3. Each of i and j represents an
integer of 1 to 3, and preferably an integer of 1 or 2. Moreover,
as described above, the organopolysiloxanes represented by the
above general formulas (5a) and (5b) contain at least two of the
above ultraviolet light-reactive groups, and consequently
f+g+n.gtoreq.2 in the formula (5a), and fi+gj+n.gtoreq.2 in the
formula (5b).
[0075] Specific examples of organopolysiloxanes represented by the
above formulas (5a) and (5b) include the compounds shown below.
##STR00003##
[0076] In the above formulas, the R.sup.9 groups are 90% methyl
groups and 10% phenyl groups.
Component (e)
[0077] The photopolymerization initiator of the component (e) has
the effect of accelerating the photopolymerization of the
ultraviolet light-reactive groups within the above component (d).
There are no particular limitations on the component (e), and
specific examples thereof include acetophenone, propiophenone,
benzophenone, xanthol, fluorein, benzaldehyde, anthraquinone,
triphenylamine, 4-methylacetophenone, 3-pentylacetophenone,
4-methoxyacetophenone, 3-bromoacetophenone, 4-allylacetophenone,
p-diacetylbenzene, 3-methoxybenzophenone, 4-methylbenzophenone,
4-chlorobenzophenone, 4,4'-dimethoxybenzophenone,
4-chloro-4'-benzylbenzophenone, 3-chloroxanthone,
3,9-dichloroxanthone, 3-chloro-8-nonylxanthone, benzoin, benzoin
methyl ether, benzoin butyl ether, bis(4-dimethylaminophenyl)
ketone, benzyl methoxy acetal, 2-chlorothioxanthone,
diethylacetophenone, 1-hydroxychlorophenyl ketone,
1-hydroxycyclohexyl phenyl ketone,
2-methyl-(4-(methylthio)phenyl)-2-morpholino-1-propane,
2,2-dimethoxy-2-phenylacetophenone, diethoxyacetophenone, and
2-hydroxy-2-methyl-1-phenylpropan-1-one. From the viewpoint of
ensuring high purity, benzophenone, 4-methoxyacetophenone,
4-methylbenzophenone, diethoxyacetophenone, 1-hydroxycyclohexyl
phenyl ketone and 2-hydroxy-2-methyl-1-phenylpropan-1-one are
preferred, and diethoxyacetophenone, 1-hydroxycyclohexyl phenyl
ketone and 2-hydroxy-2-methyl-1-phenylpropan-1-one are particularly
desirable. Any one of these photopolymerization initiators may be
used alone, or two or more different initiators may be used in
combination.
[0078] Although there are no particular limitations on the amount
added of the component (e), the amount is preferably within a range
from 0.01 to 10 parts by mass, more preferably from 0.1 to 3 parts
by mass, and still more preferably from 0.5 to 3 parts by mass, per
100 parts by mass of the component (d). Provided the amount added
falls within the above range, curing of the silicone composition
can be more readily controlled.
Addition-Curable Silicone Compositions
[0079] Specific examples of addition-curable silicone compositions
include compositions comprising:
[0080] (f) an organopolysiloxane containing at least two alkenyl
groups bonded to silicon atoms,
[0081] (g) an organohydrogenpolysiloxane containing at least two
hydrogen atoms bonded to silicon atoms (namely, SiH groups), in an
amount that provides 0.1 to 5 mols of hydrogen atoms bonded to
silicon atoms within the component (g) per 1 mol of alkenyl groups
within the entire curable silicone composition, and
[0082] (c) an effective amount of a platinum group metal-based
catalyst.
Component (f)
[0083] The organopolysiloxane of the component (f) is the base
polymer of the addition-curable silicone composition, and contains
at least two alkenyl groups bonded to silicon atoms. Conventional
organopolysiloxanes can be used as the component (f). The
weight-average molecular weight of the organopolysiloxane of the
component (f), measured by gel permeation chromatography
(hereinafter abbreviated as GPC) and referenced against polystyrene
standards, is preferably within a range from approximately 3,000 to
300,000. Moreover, the viscosity at 25.degree. C. of the
organopolysiloxane of the component (f) is preferably within a
range from 100 to 1,000,000 mPas, and is more preferably from
approximately 1,000 to 100,000 mPas. If the viscosity is 100 mPas
or less, then the thread-forming ability of the composition is
poor, and narrowing the diameter of fibers becomes difficult,
whereas if the viscosity is 1,000,000 mPas or greater, then
handling becomes difficult. From the viewpoint of ease of
availability of the raw material, the organopolysiloxane of the
component (f) is basically either a linear structure with no
branching, in which the molecular chain (the main chain) is
composed of repeating diorganosiloxane units
(R.sup.10.sub.2SiO.sub.2/2 units), and both molecular chain
terminals are blocked with triorganosiloxy groups
(R.sup.10.sub.3SiO.sub.1/2), or a cyclic structure with no
branching in which the molecular chain is composed of repeating
diorganosiloxane units, although the structure may partially
include some branched structures including R.sup.10SiO.sub.3/2
units and/or SiO.sub.4/2 units. In the above description, R.sup.10
is the same as defined below within the description of formula
(6).
[0084] Examples of organopolysiloxanes that can be used as the
component (1) include organopolysiloxanes having at least two
alkenyl groups within each molecule, as represented by an average
composition formula (6) shown below:
R.sup.10.sub.1SiO.sub.(4-1)/2 (6)
wherein R.sup.10 represents identical or different, unsubstituted
or substituted monovalent hydrocarbon groups of 1 to 10 carbon
atoms, and preferably 1 to 8 carbon atoms, and 1 represents a
positive number that is preferably within a range from 1.5 to 2.8,
more preferably from 1.8 to 2.5, and still more preferably from
1.95 to 2.05. Examples of R.sup.10 include the same groups as those
described above for R.sup.4 in the average composition formula
(3).
[0085] In this case, at least two of the R.sup.10 groups represent
alkenyl groups (and in particular, alkenyl groups that preferably
contain from 2 to 8 carbon atoms, and even more preferably from 2
to 6 carbon atoms). The alkenyl group content among the total of
all the organic groups bonded to silicon atoms (that is, among all
the unsubstituted and substituted monovalent hydrocarbon groups
represented by R.sup.10 within the above average composition
formula (6)) is preferably within a range from 50 to 99 mol %, and
more preferably from 75 to 95 mol %. In those cases where the
organopolysiloxane of the component (f) has a linear structure,
these alkenyl groups may be bonded solely to silicon atoms at the
molecular chain terminals or solely to non-terminal silicon atoms
within the molecular chain, or may also be bonded to both these
types of silicon atoms, but from the viewpoints of the composition
curing rate and the physical properties of the resulting cured
product and the like, at least one alkenyl group is preferably
bonded to a silicon atom at a molecular chain terminal.
Component (g)
[0086] The organohydrogenpolysiloxane of the component (g) contains
at least two (typically from 2 to 200), and preferably three or
more (typically from 3 to 100) hydrogen atoms bonded to silicon
atoms (SiH groups). The component (g) reacts with the component (f)
and functions as a cross-linking agent. There are no particular
limitations on the molecular structure of the component (g), and
conventionally produced linear, cyclic, branched, or three
dimensional network (resin-like) organohydrogenpolysiloxanes can be
used as the component (b). In those cases where the component (g)
has a linear structure, the SiH groups may be bonded solely to
silicon atoms at the molecular chain terminals or solely to
non-terminal silicon atoms within the molecular chain, or may also
be bonded to both these types of silicon atoms. Furthermore, the
number of silicon atoms within each molecule (or the polymerization
degree) is typically within a range from 2 to 300, and is
preferably from 4 to approximately 150. An
organohydrogenpolysiloxane that is liquid at room temperature
(25.degree. C.) can be used particularly favorably as the component
(g).
[0087] Examples of the component (g) include
organohydrogenpolysiloxanes represented by an average composition
formula (7) shown below.
R.sup.11.sub.pH.sub.qSiO.sub.(4-p-q)/2 (7)
wherein R.sup.11 represents identical or different, unsubstituted
or substituted monovalent hydrocarbon groups containing no
aliphatic unsaturated bonds and containing 1 to 10 carbon atoms,
and preferably 1 to 8 carbon atoms, and p and q represent positive
numbers that preferably satisfy 0.7.ltoreq.p.ltoreq.2.1,
0.001.ltoreq.q.ltoreq.1.0 and 0.8.ltoreq.p+q.ltoreq.3.0, and more
preferably satisfy 1.0.ltoreq.p.ltoreq.2.0,
0.01.ltoreq.q.ltoreq.1.0 and 1.5.ltoreq.p+q.ltoreq.2.5.
[0088] Examples of R.sup.11 include the same groups as those
described above for R.sup.4 in the average composition formula (3)
(but excluding the alkenyl groups).
[0089] Specific examples of organohydrogenpolysiloxanes represented
by the above average composition formula (7) include
1,1,3,3-tetramethyldisiloxane,
1,3,5,7-tetramethylcyclotetrasiloxane,
tris(hydrogendimethylsiloxy)methylsilane,
tris(hydrogendimethylsiloxy)phenylsilane,
methylhydrogencyclopolysiloxane, cyclic copolymers of
methylhydrogensiloxane and dimethylsiloxane,
methylhydrogenpolysiloxane with both terminals blocked with
trimethylsiloxy groups, copolymers of methylhydrogensiloxane and
dimethylsiloxane with both terminals blocked with trimethylsiloxy
groups, dimethylpolysiloxane with both terminals blocked with
methylhydrogensiloxy groups, copolymers of methylhydrogensiloxane
and dimethylsiloxane with both terminals blocked with
methylhydrogensiloxy groups, copolymers of methylhydrogensiloxane
and diphenylsiloxane with both terminals blocked with
trimethylsiloxy groups, copolymers of methylhydrogensiloxane,
diphenylsiloxane and dimethylsiloxane with both terminals blocked
with trimethylsiloxy groups, copolymers of methylhydrogensiloxane,
methylphenylsiloxane and dimethylsiloxane with both terminals
blocked with trimethylsiloxy groups, copolymers of
methylhydrogensiloxane, diphenylsiloxane and dimethylsiloxane with
both terminals blocked with methylhydrogensiloxy groups, copolymers
of methylhydrogensiloxane, methylphenylsiloxane and
dimethylsiloxane with both terminals blocked with
methylhydrogensiloxy groups, copolymers composed of
(CH.sub.3).sub.2HSiO.sub.1/2 units, (CH.sub.3).sub.2SiO.sub.2/2
units and SiO.sub.4/2 units, copolymers composed of
(CH.sub.3).sub.2HSiO.sub.1/2 units and SiO.sub.4/2 units, and
copolymers composed of (CH.sub.3).sub.2HSiO.sub.1/2 units,
SiO.sub.4/2 units, and (C.sub.6H.sub.5).sub.3SiO.sub.1/2 units.
[0090] The amount added of the component (g) must be sufficient to
provide from 0.1 to 5.0 mols, preferably from 0.5 to 3.0 mols, and
more preferably from 0.8 to 2.0 mols, of SiH groups within this
component (g) per 1 mol of alkenyl groups within the entire curable
silicone composition, and in particular, per 1 mol of alkenyl
groups bonded to silicon atoms within the entire curable silicone
composition, and especially per 1 mol of alkenyl groups bonded to
silicon atoms within the component (f). The proportion of the
alkenyl groups bonded to silicon atoms within the component (f)
relative to the total number of alkenyl groups that exist within
the entire curable silicone composition is preferably within a
range from 80 to 100 mol %, and more preferably from 90 to 100 mol
%. In those cases where the component (0 is the only component that
contains alkenyl groups within the entire curable silicone
composition, the amount of SiH groups within the component (g) per
1 mol of alkenyl groups within the component (f) is typically
within a range from 0.1 to 5.0 mols, preferably from 0.5 to 3.0
mols, and more preferably from 0.8 to 2.0 mols. If the amount added
of the component (g) yields an amount of SiH groups that is less
than 0.1 mols, then the time required for curing lengthens, which
is economically undesirable. Further, if the amount added yields an
amount of SiH groups that exceeds 5.0 mols, then foaming caused by
a dehydrogenation reaction tends to occur within the curing
reaction product, and the strength and heat resistance of the cured
reaction product tend to be adversely affected.
Component (h)
[0091] The platinum group metal-based catalyst of the component (h)
is used for accelerating the addition curing reaction (the
hydrosilylation reaction) between the component (f) and the
component (g). Conventional platinum group metal-based catalysts
can be used as the component (h), but the use of platinum or a
platinum compound is preferred. Specific examples of the component
(h) include platinum black, platinic chloride, chloroplatinic acid,
alcohol-modified chloroplatinic acid, and complexes of
chloroplatinic acid with olefins, aldehydes, vinylsiloxanes or
acetylene alcohols.
[0092] The amount added of the component (h) need only be an
effective catalytic quantity, may be suitably increased or
decreased in accordance with the desired curing reaction rate, and
preferably provides a mass of the platinum group metal relative to
the mass of the component (f) that falls within a range from 0.1 to
1,000 ppm, and more preferably from 0.2 to 100 ppm.
Condensation-Curable Silicone Composition
[0093] Specific examples of condensation-curable silicone
compositions include compositions comprising:
[0094] (i) an organopolysiloxane containing at least two silanol
groups (namely, silicon atom-bonded hydroxyl groups) or silicon
atom-bonded hydrolyzable groups, preferably at both molecular chain
terminals,
[0095] (j) a hydrolyzable silane and/or a partial
hydrolysis-condensation product thereof as an optional component,
and
[0096] (k) a condensation reaction catalyst as another optional
component.
Component (i)
[0097] The component (i) is an organopolysiloxane that contains at
least two silanol groups or silicon atom-bonded hydrolyzable
groups, and functions as the base polymer of the
condensation-curable silicone composition. From the viewpoint of
ease of availability of the raw material, the organopolysiloxane of
the component (i) is preferably basically either a linear structure
with no branching, in which the molecular chain (the main chain) is
composed of repeating diorganosiloxane units
(R.sup.11.sub.2SiO.sub.2/2 units), and both molecular chain
terminals are blocked with triorganosiloxy groups
(R.sup.11.sub.3SiO.sub.1/2), or a cyclic structure with no
branching in which the molecular chain is composed of repeating
diorganosiloxane units, although the structure may partially
include some branched structures. In the above description,
R.sup.11 represents an unsubstituted or substituted monovalent
hydrocarbon group of 1 to 10 carbon atoms, and preferably 1 to 8
carbon atoms.
[0098] In the organopolysiloxane of the component (i), examples of
the hydrolyzable groups other than silanol groups include acyloxy
groups such as an acetoxy group, octanoyloxy group and benzoyloxy
group; ketoxime groups (namely, iminoxy groups) such as a dimethyl
ketoxime group, methyl ethyl ketoxime group and diethyl ketoxime
group; alkoxy groups such as a methoxy group, ethoxy group and
propoxy group; alkoxyalkoxy groups such as a methoxyethoxy group,
ethoxyethoxy group and methoxypropoxy group; alkenyloxy groups such
as a vinyloxy group, isopropenyloxy group and
1-ethyl-2-methylvinyloxy group; amino groups such as a
dimethylamino group, diethylamino group, butylamino group and
cyclohexylamino group; aminoxy groups such as a dimethylaminoxy
group and diethylaminoxy group; and amide groups such as an
N-methylacetamide group, N-ethylacetamide group and
N-methylbenzamide group.
[0099] These hydrolyzable groups are preferably positioned at both
molecular chain terminals of a linear diorganopolysiloxane,
preferably in the form of either siloxy groups that contain two or
three hydrolyzable groups, or siloxyalkyl groups that contain two
or three hydrolyzable groups, including trialkoxysiloxy groups,
dialkoxyorganosiloxy groups, triacyloxysiloxy groups,
diacyloxyorganosiloxy groups, triiminoxysiloxy groups (namely,
triketoximesiloxy groups), diiminoxyorganosiloxy groups,
trialkenoxysiloxy groups, dialkenoxyorganosiloxy groups,
trialkoxysiloxyethyl groups and dialkoxyorganosiloxyethyl
groups.
[0100] Examples of the other monovalent hydrocarbon groups bonded
to silicon atoms include the same unsubstituted and substituted
monovalent hydrocarbon groups as those described above for R.sup.4
in the average composition formula (3).
[0101] Specific examples of the component (i) include the compounds
shown below.
##STR00004##
[0102] In the above formulas, X represents a hydrolyzable group
other than a silanol group, a represents 1, 2 or 3, and each of n
and m represents an integer of 1 to 1,000.
[0103] Specific examples of the component (i) include
dimethylpolysiloxane with both molecular chain terminals blocked
with silanol groups, copolymers of dimethylsiloxane and
methylphenylsiloxane with both molecular chain terminals blocked
with silanol groups, copolymers of dimethylsiloxane and
diphenylpolysiloxane with both molecular chain terminals blocked
with silanol groups, dimethylpolysiloxane with both molecular chain
terminals blocked with trimethoxysiloxy groups, copolymers of
dimethylsiloxane and methylphenylsiloxane with both molecular chain
terminals blocked with trimethoxysiloxy groups, copolymers of
dimethylsiloxane and diphenylpolysiloxane with both molecular chain
terminals blocked with trimethoxysiloxy groups, and
dimethylpolysiloxane with both molecular chain terminals blocked
with 2-trimethoxysiloxyethyl groups. Any one of these compounds may
be used alone, or two or more different compounds may be used in
combination.
Component (j)
[0104] The hydrolyzable silane and/or partial
hydrolysis-condensation product thereof of the component (j) is an
optional component, and functions as a curing agent. In those cases
where the base polymer of the component (i) is an
organopolysiloxane that contains at least two silicon atom-bonded
hydrolyzable groups other than silanol groups within each molecule,
the addition of the component (j) to the condensation-curable
silicone composition can be omitted. Silanes containing at least
three silicon atom-bonded hydrolyzable groups within each molecule
and/or partial hydrolysis-condensation products thereof (namely,
organopolysiloxanes that still retain at least one, and preferably
two or more of the hydrolyzable groups) can be used particularly
favorably as the component (j).
[0105] Examples of compounds that can be used favorably as the
above silane include compounds represented by a formula (8) shown
below:
R.sup.12.sub.rSiX.sub.4-r (8)
wherein R.sup.12 represents an unsubstituted or substituted
monovalent hydrocarbon group of 1 to 10 carbon atoms, and
preferably 1 to 8 carbon atoms, X represents a hydrolyzable group,
and r represents either 0 or 1. Examples of preferred groups for
R.sup.12 include alkyl groups such as a methyl group, ethyl group,
propyl group, butyl group, pentyl group and hexyl group; aryl
groups such as a phenyl group and tolyl group; and alkenyl groups
such as a vinyl group and allyl group.
[0106] Specific examples of the component (j) include
methyltriethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane,
ethyl orthosilicate, and partial hydrolysis-condensation products
of these compounds. Any one of these compounds may be used alone,
or two or more different compounds may be used in combination.
[0107] In those cases where a hydrolyzable silane and/or partial
hydrolysis-condensation product thereof is used as the component
(j), the amount added of the component (j) is preferably within a
range from 0.01 to 20 parts by mass, and more preferably from 0.1
to 10 parts by mass, per 100 parts by mass of the component (i). In
those cases where the component (j) is used, using an amount that
satisfies the above range ensures that the composition of the
present invention exhibits particularly superior storage stability
and curing reaction rate.
Component (j)
[0108] The condensation reaction catalyst of the component (j) is
an optional component, and need not be used in cases where the
above hydrolyzable silane and/or partial hydrolysis-condensation
product thereof of the component (j) contains aminoxy groups, amino
groups or ketoxime groups or the like. Examples of the condensation
reaction catalyst of the component (k) include organotitanate
esters such as tetrabutyl titanate and tetraisopropyl titanate;
organotitanium chelate compounds such as
diisopropoxybis(acetylacetonato)titanium and
diisopropoxybis(ethylacetoacetate)titanium; organoaluminum
compounds such as aluminum tris(acetylacetonate) and aluminum
tris(ethylacetoacetate); organozirconium compounds such as
zirconium tetra(acetylacetonate) and zirconium tetrabutyrate;
organotin compounds such as dibutyltin dioctoate, dibutyltin
dilaurate and dibutyltin di(2-ethylhexanoate); metal salts of
organic carboxylic acids such as tin naphthenate, tin oleate, tin
butyrate, cobalt naphthenate and zinc stearate; amine compounds or
the salts thereof such as hexylamine and dodecylamine phosphate;
quaternary ammonium salts such as benzyltriethylammonium acetate;
lower fatty acid salts of alkali metals such as potassium acetate
and lithium nitrate; dialkylhydroxylamines such as
dimethylhydroxylamine and diethylhydroxylamine; and guanidyl
group-containing organosilicon compounds. Any one of these
catalysts may be used alone, or two or more different catalysts may
be used in combination.
[0109] In those cases where a condensation reaction catalyst of the
component (k) is used, there are no particular limitations on the
amount added, but the amount is preferably within a range from 0.01
to 20 parts by mass, and more preferably from 0.1 to 10 parts by
mass, per 100 parts by mass of the component (i). If the component
(k) is used, then provided the amount satisfies the above range,
the composition is economically viable from the viewpoints of the
curing time and curing temperature.
Curing of Organic Peroxide-Curable Silicone Composition:
[0110] Heating the organic peroxide-curable silicone composition
causes a radical reaction to proceed and the curing reaction to
proceed, thereby curing the organic peroxide-curable silicone
composition. In terms of the temperature conditions employed for
curing the organic peroxide-curable silicone composition, because
the heating temperature used for the curing reaction is dependent
on the thickness of the coating, namely, is dependent on the
coating amount, although there are no particular limitations, the
temperature is preferably within a range from 80 to 300.degree. C.,
and more preferably from 150 to 250.degree. C. Further, secondary
curing may be performed if required, and the temperature during
such secondary curing is preferably not less than 120.degree. C.,
and more preferably within a range from 150 to 250.degree. C. The
curing time is preferably within a range from 10 minutes to 48
hours, and more preferably from 30 minutes to 24 hours.
Curing of Ultraviolet Light-Curable Silicone Composition:
[0111] Irradiating the ultraviolet light-curable silicone
composition with ultraviolet light causes the photopolymerization
initiator to react and the curing reaction to proceed, thereby
curing the ultraviolet light-curable silicone composition. In terms
of the ultraviolet light irradiation conditions, because the curing
reaction is dependent on the thickness of the coating, namely, is
dependent on the coating amount, although there are no particular
limitations, curing can typically be conducted by performing the
ultraviolet light irradiation using ultraviolet light emitting
diodes with an emission wavelength of 365 nm, under conditions
including an intensity of 5 to 500 mW/cm.sup.2, and preferably 10
to 200 mW/cm.sup.2, and an exposure dose of 0.5 to 100 J/cm.sup.2,
and preferably 10 to 50 J/cm.sup.2. Further, secondary curing may
also be conducted if required, and the temperature during such
secondary curing is preferably not less than 120.degree. C., and
more preferably within a range from 150 to 250.degree. C. The
curing time is preferably within a range from 10 minutes to 48
hours, and more preferably from 30 minutes to 24 hours.
Curing of Addition-Curable Silicone Composition:
[0112] Heating the addition-curable silicone composition causes a
hydrosilylation reaction to proceed, thereby curing the
addition-curable silicone composition. In terms of the temperature
conditions employed, because the curing reaction is dependent on
the thickness of the coating, namely, is dependent on the coating
amount, although there are no particular limitations, the
temperature is preferably within a range from 80 to 300.degree. C.,
and more preferably from 100 to 200.degree. C. Further, secondary
curing may be performed if required, and the temperature during
such secondary curing is preferably not less than 120.degree. C.,
and more preferably within a range from 150 to 250.degree. C. The
curing time is preferably within a range from 10 minutes to 48
hours, and more preferably from 30 minutes to 24 hours.
Curing of Condensation-Curable Silicone Composition:
[0113] Heating the condensation-curable silicone composition causes
a condensation reaction to proceed, thereby curing the
condensation-curable silicone composition. In terms of the
temperature conditions employed for curing the condensation-curable
silicone composition, because the heating temperature used for the
curing reaction is dependent on the thickness of the coating,
namely, is dependent on the coating amount, although there are no
particular limitations, the temperature is preferably within a
range from 80 to 300.degree. C., and more preferably from 100 to
200.degree. C. Further, secondary curing may be performed if
required, and the temperature during such secondary curing is
preferably not less than 120.degree. C., and more preferably within
a range from 150 to 250.degree. C. The curing time is preferably
within a range from 10 minutes to 48 hours, and more preferably
from 30 minutes to 24 hours.
[High-Temperature Heat Treatment of Carbon Substrate and Amorphous
Inorganic Ceramic]
[0114] The carbon substrate and the amorphous inorganic ceramic
material described above are together subjected to a heat treatment
in a non-oxidizing atmosphere at a temperature exceeding
1,500.degree. C. but not higher than 2,200.degree. C.
[0115] This heat treatment causes thermal decomposition of the
amorphous inorganic ceramic material, thus generating silicon
monoxide. It is thought that this silicon monoxide not only reacts
with the surface of the carbon substrate, but also penetrates into
the interior of the carbon substrate through pores on the surface
of the substrate, meaning the reaction generates and deposits
silicon carbide on both the substrate surface and within the
substrate pores. Accordingly, the formed silicone carbide coating
does not simply coat the surface of the substrate, but is rather
formed as a continuous coating in which the silicon carbide also
penetrates into the pores to at least a certain depth.
[0116] Because the carbon substrate and the amorphous inorganic
ceramic material are heated together within the atmosphere
described above, namely are positioned adjacent to one another
during heating, the generated silicon monoxide is able to react at
the surface of the carbon substrate.
[0117] The heat treatment is performed under a non-oxidizing
atmosphere, and preferably under an inert gas atmosphere. Examples
of the inert gas include nitrogen gas, argon gas and helium gas,
and argon gas is particularly desirable.
[0118] Further, the heat treatment is performed at a temperature
exceeding 1,500.degree. C. but not higher than 2,200.degree. C.
This heating temperature is preferably 1,600.degree. C. or higher.
Furthermore, the heating temperature is preferably not higher than
2,200.degree. C. This heat treatment causes the elimination of
silicon monoxide from the amorphous inorganic ceramic material to
start, and this silicon monoxide reacts with the carbon substrate
to form silicon carbide. If the temperature exceeds 2,200.degree.
C., then the decomposition of the carbon substrate becomes overly
vigorous, which is undesirable. The end point for the heat
treatment can be specified, for example, as the point where the
generation of silicon monoxide stops.
EXAMPLES
[0119] A more detailed description of the present invention is
presented below based on a series of examples, although the present
invention is in no way limited by these examples.
Example 1
[0120] A more detailed description of the present invention is
presented below based on a series of examples and comparative
examples, although the present invention is in no way limited by
these examples. In the examples, molecular weight values are
weight-average molecular weight values measured using GPC and
referenced against polystyrene standards. Further, the average
elemental ratio between the silicon, carbon and oxygen within the
amorphous inorganic ceramic materials is simply referred to as the
"elemental ratio".
[0121] A meltable silicone resin containing only MeSiO.sub.3/2
units as siloxane units and also having 5% by mass of silanol
groups (molecular weight: 1,000, elemental ratio: SiCO.sub.1.5,
softening point: 65.degree. C.) was placed in an aluminum Petri
dish, and was then immersed in a hydrochloric acid solution having
a concentration of 20% by mass and left to stand for two days at
room temperature. The thus obtained solid was washed with water
until the pH of the waste water reached a value of 6, and was then
dried by heating at a temperature of approximately 200.degree. C.
The thus treated solid was then heated in a non-oxidizing
atmosphere in the manner described below. Namely, the solid was
placed in an alumina boat and heated under a nitrogen gas
atmosphere inside a horizontal tubular furnace by raising the
temperature from room temperature to 1,000.degree. C. at a rate of
temperature increase of 100.degree. C./hour over a period of
approximately 10 hours, and was then held at 1,000.degree. C. for a
further one hour. Subsequently, the solid was cooled to room
temperature at a rate of 200.degree. C./hour. This process yielded
a black amorphous inorganic ceramic material. Calculation of the
ratio of the mass lost during heating relative to the mass prior to
heating (hereinafter referred to as the "heating loss") by
comparing the mass values of the amorphous inorganic ceramic
material measured before and after the heating revealed a value of
14.6%.
[0122] Measurement of the elemental ratio for the black amorphous
inorganic ceramic material by EDX analysis (Energy Dispersive X-ray
analysis) using an FE-SEM (Field Emission Scanning Electron
Microscope) yielded a result of SiC.sub.0.82O.sub.1.31.
[0123] Further, measurement of the hydrogen mass fraction relative
to the total mass of the amorphous inorganic ceramic material
(hereinafter simply referred to as the "hydrogen mass fraction'")
by FE-SEM EDX analysis yielded a result less than the detection
limit of 0.5% by mass.
[0124] 50 g of the thus obtained amorphous inorganic ceramic
material, and a substrate composed of a CIP (Cold Isostatic
Press)-treated circular cylindrical carbon molded item (diameter:
15 mm.times.length: 50 mm.times.thickness: 2 mm) were placed in a
container formed from carbon, which was then placed inside an
atmosphere furnace, and under an atmosphere of argon gas, the
temperature was raised to 2,000.degree. C. over a 20-hour period at
a rate of temperature increase of 100.degree. C./hour. The
temperature was then held at 2,000.degree. C. for two hours, and
then cooled to room temperature, yielding a yellow-green solid on
both the inner and outer surfaces of the circular cylindrical
molded item. The mass of the circular cylindrical material
following heating had increased by 5%. Further, the dimensions of
the circular cylindrical material following heating were diameter:
15 mm.times.length: 50 mm.times.thickness: 2.1 mm.
Measurement of Elemental Ratio
[0125] A sample of the yellow-green solid surface coating layer
(deposited layer) was scraped off the circular cylindrical
material, and when this sample was subjected to a carbon analysis
using a carbon analyzer (product name: CS-444LS, manufactured by
LECO Corporation), the carbon mass ratio was 30.3% by mass.
Further, when a similarly collected sample was subjected to an
oxygen analysis using an oxygen analyzer (product name: TC436,
manufactured by LECO Corporation), the oxygen mass ratio was not
more than 0.2% by mass. The elemental ratio was
Si.sub.1C.sub.1.02.
Example 2
Materials
[0126] (A) 100 parts by mass of a diorganopolysiloxane containing
alkenyl groups within each molecule, represented by a formula shown
below:
##STR00005##
wherein n and m are numbers such that n/m=4/1 and the viscosity of
the siloxane at 25.degree. C. is 600 mPas.
[0127] (B) 0.5 parts by mass of benzoyl peroxide.
[0128] (C) 33 parts by mass of a diorganopolysiloxane containing
hydrogen atoms bonded to silicon atoms, represented by a formula
shown below.
##STR00006##
[0129] The above components (A) to (C) were combined in a planetary
mixer (a registered trademark, a mixing device manufactured by
Inoue Manufacturing Co., Ltd.), and were stirred for one hour at
room temperature, yielding a curable silicone composition with a
viscosity at room temperature of 1,000 mPas.
[0130] This curable silicone composition was heated at a
temperature of approximately 200.degree. C. for 30 minutes to
obtain a silicone cured product. This silicone cured product was
then heated under a non-oxidizing atmosphere in the same manner as
that described for example 1, yielding a black amorphous inorganic
ceramic material. The heating loss was 16.7%.
[0131] Measurement of the elemental ratio of this amorphous
inorganic ceramic material by EDX analysis (Energy Dispersive X-ray
analysis) using an FE-SEM (Field Emission Scanning Electron
Microscope) yielded a result of SiC.sub.1.3O.sub.1.4.
[0132] Further, measurement of the hydrogen mass fraction relative
to the total mass of the amorphous inorganic ceramic material
(hereinafter simply referred to as the "hydrogen mass fraction") by
FE-SEM EDX analysis yielded a result less than the detection limit
of 0.5% by mass.
[0133] 50 g of the thus obtained amorphous inorganic ceramic
material, and a substrate composed of a CIP-treated circular
cylindrical carbon molded item (diameter: 15 mm.times.length: 50
mm.times.thickness: 2 mm) were placed in a container formed from
carbon, which was then heated in an atmospheric furnace and
subsequently cooled to room temperature in the same manner as that
described for example 1, yielding a yellow-green solid on both the
inner and outer surfaces of the circular cylindrical molded item.
The mass of the circular cylindrical material following heating had
increased by 5%. Further, the dimensions of the circular
cylindrical material following heating were diameter: 15
mm.times.length: 50 mm.times.thickness: 2.1 mm.
Measurement of Elemental Ratio
[0134] A sample of the yellow-green solid surface coating layer
(deposited layer) was scraped off the circular cylindrical
material, and when this sample was subjected to a carbon analysis
using a carbon analyzer (product name: CS-444LS, manufactured by
LECO Corporation), the carbon mass ratio was 30.2% by mass.
Further, when a similarly collected sample was subjected to an
oxygen analysis using an oxygen analyzer (product name: TC436,
manufactured by LECO Corporation), the oxygen mass ratio was not
more than 0.2% by mass. The elemental ratio was
Si.sub.1C.sub.1.00.
Analysis of Impurity Elements
[0135] With the exception of treating 5 g of the above curable
silicone composition inside a carbon container without impregnating
the silicone composition into a porous carbon substrate, curing and
heat treatment were conducted in the same manner as that described
above, yielding a green solid. When this solid was analyzed by ICP
emission analysis, the results shown in Table 1 were obtained for
the various element content values. A result of "<0.1" indicates
that the result was less than the detection limit of 0.1 ppm.
TABLE-US-00001 TABLE 1 Analyzed element Measured value (ppm) Fe
<0.1 CR <0.1 Ni <0.1 Al <0.1 Ti 0.1 Cu <0.1 Na 0.1
Zn <0.1 Ca 0.1 ZR <0.1 Mg <0.1 B <0.1
[0136] These results revealed that nickel, chromium, iron and
aluminum, which are impurity elements that typically cause problems
in the field of semiconductor devices, were all less than the
detection limit.
INDUSTRIAL APPLICABILITY
[0137] The silicon carbide-coated carbon material obtained using
the method of the present invention exhibits excellent heat
resistance and creep resistance, and is therefore very useful as a
high-temperature material. For example, the silicon carbide-coated
carbon material can be used in the field of semiconductor
production, as a material for boards and process tubes that are
used within steps for conducting heat treatments of semiconductor
wafers, or conducting thermal diffusion of trace elements within
semiconductor wafers.
* * * * *